Motor fuel



pression ratio is much lower than the desired Patented May 2, 1933UNITED STATES PATENT OFFICE LUDWIG ROSENSTEIN AND WALTER J". HUND, OFSAN FRANCISCO, CALIFORNIA MOTOR FUEL No Drawing.

This invention relates to motor fuels, and deals particularly with theuse of substances which, when added to gasoline or other fuel, willeffect diminution of elimination or 5 knocking, together with anincrease in the efficiency of the motor fuel.

Most of the fuels now produced for automobile consumption have a lowcompression ratio: that is to say, their highest useful comratio forordinary operating conditions. Under conditions metwith in theoperationof automobiles, where low compression motor fuels are used, knocking ordetonation of the fuel very frequently occurs. This causes a decreasein-the motor efficiency and gives rise to the disagreeable impressionthat the various motor parts are loose. It has been customary to add tolow compression fuels various substances which tend to raise the maximumcompression ratio of the fuel, with a diminishing ofthe fuel knock, andwith the effecting of a more satisfactory engine operation. Many ofthese substances are undesirable for the reason that they arecomparative- 1y expensive, and their incorporation into commercialgasolines is impractical for this reason. Other compounds whicheliminate knocking are unsatisfactory because of the fact thatby-products of combustion, caused by interaction with the compoundsadded, leave deposits in the engine, which interfere considerably withits proper running.

5 It is an object of our invention. in general,

to increase the efliciency of motor fuels by the addition of seleniumcompounds. It is a further object of our invention to utilize selenium-compounds of the form of diselenides. in

5 It is a further object of our invention to make use of the distinctcharacteristic color of diselenides for tinting gasoline. Fuelscontaining diselenides, even in the smallest concentrations, possess adistinctive yellow color which is useful for distinguishing fuels inApplication filed August 27, 1930. Serial No. 478,305.

which compounds of this type are incorporated.

It has generally been suggested in the art that certain types ofselenium compounds might be made use of to prevent detonation of motorfuels. These compounds, suggested by the prior art, are monoselenidecompounds. They are impractical for use as anti-knock agents for thereason that, although the monoselenide compounds ing the highest usefulcompression of the fuel very considerably, the anti-knock effect of thediselenide compounds being very much in excess of that possessed by anyof the selenides heretofore known to be useful.

.The diselenides possess properties which are quite distinct from thoseof other selenium compounds. They are for the most part solid,crystalline bodies, imparting to gasoline solutions a distinctive yellowcolor, in even the smallest concentrations; they are, furthermore,relatively non-volatile substances, whereas the selenium compoundsheretofore known to the art are highly volatile. In stating that thediselenides are non-volatile, it is meant that their degree ofvolatility is markedly less than that of the least volatile hydrocarbonconstituents of the fuel. This chromophoric effect is very useful inimparting to gasolines an identifying color characteristic, dispensingwith the use of added dyestuffs for this purpose.

. The diselenidecompounds utilized accordmg to our invention have theadditional advantage that they are non-reactive with respect to thehydrocarbon mixture into which they are introduced. This insures afunctionheretofore described in the art have some anti-knock value,

ing of the anti-knock compound which is inde pendent of the type ofgasoline used. Many substances used as anti-knocks in the prior art areunsatisfactory because their effect varies considerably with the type ofgasoline into which they are introduced. Furthermore, they areoftentimes highly reactive substances and for this reason are unstable.It is of great advantage to prepare anti-knock fuels in which a standardamount of nondetonating compound may be introduced into any type ofgasoline to give a standard effect.

A further advantage accompanying the use of dise'enide compounds, whichis true of selenium compounds in general, resides in the fact that noresidues are formed during combustion which will interfere with theproper-functioning of the engine. One of the biggest disadvantages ofcertain antiknock compounds known to the art lies in the fact that manyinsoluble solid compounds are formed during combustion which deposit inthe engine, greatly reducing its efficiency and which are extremelydifficult to remove. The diselenide compounds, when used asantidetonation agents, form no such injurious deposits. Their use may becontinued for an extended period'of time without interfering in any waywith the proper engine operation.

The general classof compounds embraced for-use in our invention may beillustrated by the following typical formula:

R and R in this formula may represent either organic or inorganicresidues. The organic residues which may be attached to the seleniumatoms may be either aromatic or aliphatic. In other words, where thecharac teristic diselenide grouping is present in the compound, thenature of the substituent groups which are attached to the selenideatoms is practically immaterial.

As an example if diselenides which may contain inorganic residuesdirectly attached to the selenium atoms, we have used NC-SeSeSe-CN andNC-Se-Se-CN, both of which possess a very high anti-knock value. Theyare likewise soluble in gasoline to the extent necessary for impartingto the fuel the desired high compression capacity. Other diselenideshaving inorganic radicals incorporated in the complex have been found tobe satisfactory in every respect for the purposes of our invention. 'Wehave found, ho w ever, that of this particu'ar class of diselenides, theseleno cyanates have proven to be more satisfactory than most of theother compounds within the class. Wherever the term cyanates is used, itis meant to include the isocyanates as well. Likewise, wherever the termnitrile is used. the term will he meant to include isonitrile. Similarlythe groups CN and NC are used, these groups are used to illustrate bothnitrile and isonitrile groups. This interpretation of these variousterms will be adhered to throughout the specification and claims.

Diselenidecompounds having organic substituents within the moleculeshave been found to be very satisfactory. The aryl substituted compounds,we have found, have decided anti-knock properties. Within this class isor diphenyl diselenide. Obviously, other aryl residues may besubstituted in place of the phenyl group. Furthermore, the aromaticnuclei may contain additional substituent groups, for example, amino,nitrile, isonitrile, alky, and in general, the usual substituents whichmay be included in an aromatic nucleus. \Ve have found amino diphenyldiselenide,

or dianilino diselenide, to possess highly satisfactory anti-detonatingproperties.

The diarnino substitutes of diphenyl diselenides may take the form ofsecondary or tertiary amines. Compounds of this type are exemplified inI 1 I H {H and CH3 CH3 flQ O K CH3 CH3 which are alkylated forms of thediamino diphenyl diselenides. Other substituent radlcals than methyl maydisplace the hydrogen atoms of'the amine groups.

Derivatives of the diselenides formed by attaching aliphatic radicals tothe Se atoms,

possess very high anti-detonating effect. As i typical of thesesubstances, I have found 0 21 15 Se- Se (3 H tics.

V the Our invention also contemplates 1n WhlCh use of selenium compoundsthe groups attached to the different selenium atoms are not. identical.For example, upon one selenium atom may be an organic group, and uponthe other'selenium atom may be an inorganic group. Where both seleniumatoms have attached thereto organic groupings, one of the substituentsmay be an aliphatic radical and the other may be an aromatic radical.Furthermore, where the substituents attached to the selenium atoms areeither bothv aliphatic or both aromatic, the substituted groups maydiiier; for example, where alkyl groups areattached to both soleniumatoms, one such group may be a methyl radical, and the other group maybe an ethyl radical. -Where both substituents are aromatic, one may be asubstituted aromatic group and the other may be an unsubstitutedaromatic group one of thegroups may be polycyclic and one of the groupsmonocyclic, and widely varying changes may be made similarly withoutdeparting from the spirit of our invention.

. Mention has already been made of the fact I that the diselenide groupis chromophoric and imparts a distinctive golden yellow tint togasoline. This color intensity is enormously increased by the attachmentto the diselenide group of amine groups, particular I In the followingtable are illustrated the effects of various concentrations of diphenyldiselenide upon the compression value of a Los Angeles straight rungasoline, taken upon the basis of benzol equivalent, benzol.

being taken as the standard of comparison due to its well knownanti-knock qualities:

Diphen l Highest diseleni e t g g useful com m 1 M01 pressjon 55 litreratio A study of the above table showsthat without the addition of thediphenyl diselenide, the highest useful compression for the gasolinetaken for the purposes of comparison was 5.43. In order to bring up thecompress ar yto add only 5 grams of diphenyl diselenide per litre offuel. This was found to be equivalent to a benzol content of 31%,necessary to produce an equivalent result in the gasoline used. Theeffectiveness of the diphenyl diselenide as an anti-knock agent, istherefore obvious.

, It has been suggested in the art that diphenyl selenide has someutility as an antimock agent. The following table illustrates acomparison between diphenyl selenide and diphenyl diselenide, showingthe anti-detonating effect of the .diselenide to'be far in excess ofthat of the monoselenide:

Diphenyl Di henyl Highest useful com- Benzol equivadiselenide se enidepression ratio lent percent Gram Gram Di- Di- Di- Diatoms selatomsselphenyl phenyl phony] phenyl enid per enid per diselemonoseldisele-.monosellitre litre nide enide mde enlde Percent Percent 032 0214 6. 0 5.57 31 10 .016 0107 5. 68 5. 50 16 6 008 00535 5. 53 5. 45 8 2 004 002675. 49 5. 44 5 1 The effectiveness of the diselenide compounds is manytimes that of the monoselenide per gram atom of selenium in thecompound.

The above tables have taken diphenyl diselenide as the basis. This ismerely by way of illustration. The other diselenides are known to workin substantially the same way as diphenyl diselenide. For example, d1-ethyl diselenide,

' in the concentration of 5 g. per liter of gasoline, has been found tobe the equivalent of 40% benzol, and is therefore 80 times as effectiveas benzol.

Symmetrical-para-dimethyl-anilino-dlselenide:

in the concentration of 2.5 grams per liter is equivalent to 22% benzol.Therefore it is 88 times as effective as benzol.

Symmetrical-para-dimethyl-anlllno-dlselenide:

alent to 35% benzol. Therefore, it is 70 times as effective as benzoLlMany changes may be made in the structural complex of the .diselenidecompounds. I Any such changes are considered to be with- 2. A highcompression motor fuel containing an amino diphenyl diselenide.

3. A high compression motor fuel containing a dianilino diselenide.

5 4. A high compression motor fuel containing symmetrical paradimethyl-anilino-diselenide.

5. A high compression motor fuel containing an amino derivative of adiselenide. 6. A high compression motor fuel containing an aminosubstituted aromatic derivative of a diselenide.

7. A high compression motor fuel containing an amino substitutedaliphatic derivative of a'diselenide. J

8. A high compression motor fuel containing an amino substituted diarylderivative of a diselenide. 9. A high compression motor fuel containingan amino substituted dialkyl derivative of a diselenide.

10. A high compression motor fuel containing an asymmetrical diselenide.

In testimony whereof, we afiix our signatures. g x j LUDWIG'ROSENSTE I N

